1. Field of the Invention
This invention relates generally to intraocular lenses, and pertains more particularly to a focusable intraocular lens which is substituted for a defective (usually cataractous) natural lens of a human eye.
2. Description of the Prior Art
Various nonfocusable or nonaccommodating intraocular lenses have been devised and rather extensively utilized. One such lens is disclosed in U.S. Pat. No. 4,466,705, issued on Aug. 21, 1984 to Paul E. Michelson for "FLUID LENS." In this instance, a semipermeable sheath having anterior and posterior portions, which portions are joined at their peripheral edges, contain therein a body of liquid. The interior of the sheath is kept full of liquid by osmosis, the liquid in this way determining the refractive power of the lens. The refractive power, however, is not variable.
Lenses of hard plastic have also been devised and used. As an example, reference may be made to U.S. Pat. No. 4,328,595 granted on May 11, 1982 to John H. Sheets for "INTRAOCULAR LENS." This patent depicts a typical plano-convex hard plastic lens that is held in place by means of spring loops. It is of the non-accommodating or non-focusing type in that the lens is simply implanted after the natural lens capsule has been removed.
A more complex and sophisticated system is described in U.S. Pat. No. 4,373,218 issued on Feb. 15, 1983 to Ronald A. Schachar for "VARIABLE POWER INTRAOCULAR LENS AND METHOD OF IMPLANTING INTO THE POSTERIOR CHAMBER" in which the optical characteristics are determined by varying the amount of fluid contained in an expansible sac in one instance, or by means of a controlled voltage in another instance where the contents of the sac constitute a liquid crystal material.
In still another patent, this being U.S. Pat. No. 4,253,199 granted on Mar. 3, 1981 to Anton Banko for "SURGICAL METHOD AND APPARATUS FOR IMPLANTS FOR THE EYE," the natural eye lens is removed along with the anterior portion of the natural capsule. In this situation, the implant capsule is comprised of peripherally sealed pieces or walls that are connected to the ciliary body by means of sutures. The ciliary body provides the muscular action in order to produce different degrees of accommodation.
None of the above patented arrangements, or others known to me, envisage the retention of the biologically provided capsule or bag belonging to a human eye, and replacing the natural lens that has become defective for some reason with a readily deformable lens in which the anterior and posterior walls thereof are normally biased outwardly in a bulging relation with respect to each other, but which can be flattened or caused to move closer together by the natural capsule that has been left within the eye and also the muscle-acting zonules that nature has provided and which also are left within the eye so that they can exert a tensional pull on the natural capsule with the consequence that an artificial lens can be flattened so as to change the refractive index thereof.